Piston



(No Model.)

' P. MGFADDBN.-

HsToN.' No. 260,308. Patented June 27,1882.y

l.;h\ uTnD STATI-gsV PATENT v OFFICE.

.FRANOISMCFADDEN, OF BALTIMORE, MARYLAND, ASSIGN OR OF ONE-HALF TOROBERT RYNEHART, 0F SAME PLAGE.

*P I 'S TO'N SPECIFICATION forming part, ofLetters/PatentL-No.-260,303,.dated. June 27, 1882.

I Application filed April 20, 1882. v (No model.)

To all-"whom tt may-concern: n

Be it known that I, FRANCIS MGFADDEN, a citizen `of ythe UnitedStates,residing at'Baltimore, in theState .ofMaryla'nd, have inventedcertainnew'nnd useful Improvements in Pistons,of vwhich the following isa specification, reference being had therein to the accom-panying'drawings.

-My invention` relates to certain improvements in pistons, and willIfirst be described, and Vthen designated in" the claims.

In the drawings hereto annexed, Figure 1 is a view of the piston, thefollower iside being removed. Fig. 2 is an inner side viewV ofthe`follower,'showingthesegment shape of the depressors. Fig. 3`is adiametrical section of the piston. Fig. 4. is a side view oftheadjustinghub. Fig. 5 is a sectional view of a` cylinder containing thepiston.

The letter A designates the head, having a flange, b, on one side of itsrim. This head servesas one side of the piston.

C is the follower or opposite side of the piston, and its rimconstitutes the other flange of the piston. Between the flange-s of thetwo sides are the packing-rings D.

The-inner face of the head is provided with an annular groove, c,concentric with the axis of the head. In practice the dimension,measuring diametrically from side to side of the groove, should be aboutone-third that of the piston. For an ordinary-sized piston-say from sixto twelve inches in diameterthe annular groove would have a depth ofabout aquarter of an inch.

Extending outward from the innermost side of the annular groove areradial grooves d, in

the present instance five in number. These m radial grooves have a depthfrom the face A to a plane coincident with the ange b. That part of thehead which constitutes the periphery A? on the inner side of the llangeb has a recess, e, at the end of the radial groove. That part f of themetal between the recesses isleft intact or projecting to the periphery.

The metal packing-rings D- are between the two peripheral flanges, andsaid rings are cut, as l.shown at g, to permit of their expansion. Abar, E, is iitted to slide in each of the radial grooves, and theoutermost end of each bar is connected toa half-elliptic shape spring,h,

Mwhose two ends bear against the inner side of the factth'atntheinnermost end of the sliding bars is beveled or-inclined, as at i. Awedge,

7c,- 'occupiesthe-innermost end of each radial 60 groove andrrcs-tsuponthe inclined end of the sliding bar. The wedge is capable of movingin the direction of a `lineextending straight through-the'lpistonparallelwith the pistonrod. f Uponthefwedgebeingforced in this direc- 65 tion `thebar E moves outward and causes the spring'to press againstand expand the rings.

An adjusting-hub consists of a circular plate, F, having on theouterflat side a centralboss with a square socket, n, into which a key may 7obe inserted for turning the hub. On theinner dat side of the circularplate, and near the rim, are segment or curve shaped inclines p, live innumber, to correspond with the same number of sliding bars and wedges.lAny one of the bars E may have the inclined end and the wedge whichbears against it so varied in inclination that the partial turn of thehub will move some of the radial bars E outward more than others.Thereby, if desired, when the 8o and are thereby adapted to occupy theannular 8 5 groove c in the head. The rim of the circular plate isprovided with ratchet-teeth q. j

The follower or side C of the piston has a central opening, throughwhich the boss ofthe adjusting-hub projects. Upon the inner side 9o orface ofthe follower, around the central opening, is a recess capable ofreceiving the circular plate F, as seen in Fig. 3, and a'smaller recessat one side contains a pawl, r, against which bears a spring, s. Thepawl engages with the ratchet-teeth on the rim of the circular plate,and holds the adjusting-hub from turning back and prevents thecontraction of the rings.

All the parts here described are shown in :oo

their respective positions in Fig. 3. It will be seen that the inclinedface of each depressor p rests upon the large end of one of the wedgesk. The least partial turn of the hub-that is, a turn sufficient to passone of the ratchet- `teeth on the pawl-causes the inclined face of thedepressor to move over the end of the wed ge, and has the eil'ect todepress the wedge into the radial groove d, and by causing said wedge topress against the inclined end of the bar E the latter is moved outwardand presses the spring h, which is at its outermost end, against thepacking-rings D, thus causing them to expand against the inner wall ofthe cylinder. The expansion of the packiug-rin gs is thus et'- fected bythe combination of devices herein described.

The construction here described as applied for the expansion ot' thepacking-rings of a steam-piston may also be utilized in water suction orforcing apparatus.

In Fig. 5 a sectional view of a cylinder is shown containing my improvedpiston.

The letter L designates the cylinder, D the packing-rings of the piston,and t the pistonrod. The head of the cylinder has a central hole closedby a cap or screw-plug, u.. By removing this plug a key may be enteredthrough the central hole, and the adjusting-hub on the piston maythereby be turned to expand the packing-rings without removing thecylinderhead. The arrangement, therefore, of the pist0n having anadjusting-hub with a socket or equivalent means adapted for theattachment of a key, and the central hole in the cylinderA head for theentrance of the said key, enables the packing-rings of the piston to beadjusted without delay or inconvenience.

The adjusting-hub F of applicant and the ratchet-tooth q on its circularplate t into and occupy a recess on the inner side of the follower-plateC, while a pawl, r, and spring s occupy a recess also on the inner sideof the plate C.

Having described my invention, I claim and desire to secure by LettersPatent of lthe United States- A piston consisting,r of a flanged headprovided with an annular groove concentric with its axis, and withradial grooves extendingout- Ward from the annular groove, a follower, aseries of expausible packing-rings between thc head and follower,laterally-slidin g bars Within the radial grooves, springs interposedbetween the sliding bars and packingrings, a circular plate between thehead and follower, provided with a central boss adapted to receiveawreuch or key, and with a series of circularly-arrangeddownwardly-projecting inclined lugs or teeth, a series of wedgesinterposed between the circular plate and thelaterally-sliding bars, anda ratchet mechanism for retaining the circular plate, substantially asdescribed.

In testimony whereof I affix my signature in presence of two witnesses.

FRANCIS. MCFADDEN.

Witnesses:

JNO. T. MADDoX, WM. H. RYNEHART.

